English

Extensions of discrete Helly theorems for boxes

Combinatorics 2024-04-23 v1

Abstract

We prove extensions of Halman's discrete Helly theorem for axis-parallel boxes in Rd\mathbb{R}^d. Halman's theorem says that, given a set SS in Rd\mathbb{R}^d, if FF is a finite family of axis-parallel boxes such that the intersection of any 2d2d contains a point of SS, then the intersection of FF contains a point of SS. We prove colorful, fractional, and quantitative versions of Halman's theorem. For the fractional versions, it is enough to check that many (d+1)(d+1)-tuples of the family contain points of SS. Among the colorful versions we include variants where the coloring condition is replaced by an arbitrary matroid. Our results generalize beyond axis-parallel boxes to HH-convex sets.

Keywords

Cite

@article{arxiv.2404.14308,
  title  = {Extensions of discrete Helly theorems for boxes},
  author = {Timothy Edwards and Pablo Soberón},
  journal= {arXiv preprint arXiv:2404.14308},
  year   = {2024}
}

Comments

13 pages, 1 figure

R2 v1 2026-06-28T16:02:29.047Z